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R. G. wQoDs 2 Sheets-Sheet 1 Filed Feb. 15. 1954 s. ww

IN VEN TOR. R085? 7' GLEN WOODS Feb. 14, 1956 R. G. wooDs 2,734,411

PREDETERMINED TORQUE RELEASE SOCKET lWRENCH Filed Feb. 15, 1954 2 Sheets-Sheet 2 62 /16 z (/8 wm/v 38 720 H :m I I'xm n 1 mh Il UM. Nw .M N@ I INVENTOR. ROBERT GLEN wooDs United States Patent O Mice 2,734,411 PREDETERMINED TORQUE RELEASE SOCKET WRENCH Robert Gien woods, Huntington Park, Calif. nssignnr in oa-lllnlenools Inc., South Gate, Calif., a corporation of Application Febrnnry 15, 1954, serial Nn. 410,113 6 claim. (cl. :s1-52.4)

' The present invention relates generally to wrenches and more particularly-to an improved form of adjustable torque wrench.

A very large number of adjustable torque wrenches are undergoing daily use in many industries. Generally, these adjustable torque wrenches include a load-engaging member and a spring which resists the movement of the load-engaging member until a desired amount of torque is applied thereby. The imposition of such torque upon theload-engaging member overcomes the force of the spring and the latter is deformed, thereby permitting a limited movement of the load-engaging member to occur. Such movement provides an indication that a desired amount of torque has been applied to the load.

After aA certain amount of usage, it becomes necessary to replace the original spring with a new one. This involves a major ditlculty, because of the wide variation in spring rates encountered with commercially available springs. While all springs of a similar commercial classification ostensibly have identical characteristics, as a practical matter this is not true. The spring rates of such springs `actually vary widely from one another. Because of such spring rate variation, it is often impos' sible to satisfactorily eiect calibration of the wrench by adjustment of the spring alone.

A major object of the present invention is to provide a new and' improved torque wrench of the adjustable type.

Another object is to provide an adjustable torque wrench having novel means to compensate for the wide variation in the spring rates of commercially available springs.

An important object of the present invention is to provide an adjustable torque wrench of compact size and light weight which is economical of construction. This object is accomplished in part by the provision of a wrench capable of utilizing a spring of minimum size and strength for a maximum load-applying rating of the wrench.

An additional object of the invention is to provide an adjustable torque wrench which is simple of design and rugged of construction whereby it may provide a long and useful service life.

These and other objects and advantages of the present invention will become apparent from the following detailed description, when taken with the appended drawings, wherein:

Figure'l isa top view of a preferred form of adjustable torque wrench embodying the present invention, the top of said lwrench being broken away in horizontal section so as'to illustrate its internal construction;

Figure 2 is an enlarged vertical sectional view taken on line 2--2 of Figure 1;

Figures 3 and 4 are horizontal sectional views taken on lines 3-3 of Figure 2 inorder to illustrate the movement of `the parts of said wrench during a torque-apply` ing operation; and, i

UFigure 5 is a section, partly broken away on lines 2,734,411 Patented Feb. 14, 19516 the head 10; a generally rearwardly extending arm 18l rigidly secured to the load-engaging member 16; a tripping lnger 20 pivotally mounted by the head 10 for ro- 4 tation toward and away from the free end of the arm 18; and, a spring 22 attached to the free end of the tripping inger 20 so as to constantly bias itsintermediate portion into contact with the free end of the arm 18. The tripping finger 20 and spring 22 resiliently resist counter-clockwise rotation of the free end of the arm 18 as torque is applied to an object, such as a bolt head, by theA load engaging member 16.- Such torque is applied by moving the lever 12 in a clockwise direction from its position of Figure 1.

More particularly, the front end of the head 10 mounts a suitable bearing 24 for supporting a shaft 26. The shaft 26 in turn serves to rigidly couple the loadengaging member 16 and the front of the arm 18. The load-engaging member 16 may include a socket 28 for receiving the head of a bolt. However, this member may take other forms without departing from the scope of the invention. Stop elements 30 and 32 may be disposed at either side of the arm 18 for restraining movement thereof beyond its two positions of Figures 3 and 4. The free end of the arm 18 mounts a roller 34 by means ofV a vertically extending pin 36.

The tripping linger 20 is pivotally'secured to one side of the head 10 adjacent the free end of the arm 18 by a vertically disposed pivot pin 38. The intermediate portion of this linger is formed with a pointed projection 40 that is in contact with the periphery of the roller 34. The tripping nger 20 is formed with a threaded bore 42 between its free end and the pointed projection 40 for receiving a set screw 44. The purpose of this set screw 44 will be fully set forth hereinafter. The free end of the tripping lever is formed with a hole 46 to receive one end of the spring 22.

The spring 22 is Yof the helical tension type and its front end is secured to a exible element such as a cable 48. From its point of attachment to the spring 22, the cable 48 extends around a pulley or sheave 50 that is mounted below the arm 18. As shown in Figure 1, the cable extends rearwardly from the pulley 50 through the interior of the lever 12 to a hook 52 mounted by the handhold 14 at the rear of the lever.

The handhold 14 is of tubular configuration and itsr inner periphery is formed with internal threads 54 which are engaged with complementary external threads 56 formed on the rear portion of the lever 12. Accordingly, rotation of the handhold upon the lever will eiect concurrent axial movement of the handhold relative to the lever. The rear end of the handhold 14 mounts a bearing S8 that supports the hook 52. With this arrangement, rotation of the handhold upon the lever will serve to stretch or contract the spring 22 by virtue of the latters attachment to the cable 48. In order to provide a visual indication of the relative positions of the lever 12 and the handhold 14, suitable Vernier graduations 60 may be applied to these members. These vernier graduatons may read in inch-pounds or foot-pounds and should be so coordinated with the spring rate of the spring 22 and thc geometry of the wrench as to provide a visual indication of the amount of torque being applied by the loadengaging member 16 when the arm 18 begins a counterclockwise movement. Hence, before a bolt-tightening the arm roller 34-by means of thejtrippingfinger 2t).v

When the resistance of the boltphead 24 againstfurther tightening reachesthe desired value, however, the roller 34 will cam the tripping finger; in.,a,counterclockwise direction to its positionof Figure4-,the stopqelement 30 restraining further movement of thepartsoncoit engages the side of the head-at 62. Suchgmovementofzthe arm 18. and the tripping finger. provide Van indication that the desired amount of torque has been` applied to the bolt head.

As notedpreviously h'ereinbefore;.,itfwill periodicallyy be necessary to calibrate the wrench for the particular spring 22 being rutilized therewith.. The -presentinvention contemplates novel means for effectingsuch calibration,v

which means includes the set screw. 44 mounted by the tripping fingerV 20.

Referring toV Figure 3, it shouldbe noted that the initial amountof force yapplied by the/spring 22 to the -arm roller. 34througl1` thetripping lever 20 is determined by the, point of `contactof the. projection 40. relative. to the arm.

roller. Thefarther. this point of 'contactis moved to the leftfrom'its position of Figure. 3, the greater. the force which must `be initially overcome by the spring to initiate counterclockwise movement of the arm 18. Conversely, thefarther this point of contact is moved to the right from its position of Figure. 3, the smaller the force which must be initially applied to the arm roller 34 by tht spring 22 to initiate such movement. The position of the projection relative to the arm roller determines the wedging angle existingbetween these members. Control over the position of this point of contact is effected by means of the set screw 44. Rotating the set screw so as to move it toward the arm roller 34 moves the'point of contact to the right in Figure 3, while rotating it in the opposite directionmoves the point of ycontact to the left in Figure 3.

The amount of tensile force initially applied by the spring 22 to the arm roller 34 determines the amount of torque required to initiate counterclockwise movement of the arm 18. It isessential that for any chosen torque value the particular spring 22 being utilized exert the same initial tensile force despite the fact that the spring rates of such springs are likely to vary considerably. Because of the provision of the set screw 44, it is possible by varying the point of 'contact between the projection 40 and the arm roller 341to apply to the arm 18 the same torque resistinggforceper unit of spring expansion regardless of arvariation in the spring rate of the springbeing utilized.

Referring now toFigure 5, there is shown a modified form of armroller and tripping finger construction. The modified arm roller 34T is seen to be formed with a notch 64.wherein is disposed the projection 40' of the tripping.

finger Preferably, the projection 40- will not be pointed, but instead will be formed with a slight radius. Withthisarrangcment, a lower unit loading between the trippingY lever projectionA 40 and the arm roller 34' is made'posisble. Thisis true since the modified form provides al surface to surface contact'between the arm roller and the projection rather than a line-to-line Contact. More accurate results are also possible'withthis modified form since the trippingv finger 20 must necessarily always return. to the same location on the arm roller-34 after each. torque-applyingoperation.

It will be apparent that various. modifications; andchanges may be made with respect to the adjustable. .torque wrench constructionhereinabove described without departing from the spirit of the present invention or thescope of the following claims.

I claim:

l. An adjustable torque wrench, comprising: a head; a load-engaging member pivotally mounted at the front portion of said head; a lever extendingjaway from the rear of said head; a rigid arm member rigidlysecuredto'said load-engaging member and extending generally rearwardly therefrom; a trippingtinger. pivotally mounted; on. said: head and formed with, a pointed projectionat itsintcrmediate portion; a set screw mounted on said .tripping finger between itsl free end and said projection that normally engages'the free end of'said varm'rneinber-'so as to control the wedging angle between said projection and the free end of said arm member; and tension spring means interposed between the free end of said finger and said head for constantly biasing saidprojectionforwardiy into contact with the. free. endofsaid armmember.

2. An adjustable torque wrench, comprising: a head;A a load-engaging member pivotally mounted at the,.front portion of said head; a lever extending away from therear;

ofsaid head; threads formed on the rear portion of said lever; a handhold threadedly carried upon the threads of. said lever; a bearing mounted onvsaid handhold; ahool: carried by said bearing; a rigidv arm member rigidlyl secured to said load-engaging memberl and extendinggemv erally rearwardly therefrom; a roller mounted on the rear end of said arm member; a tripping-finger pivotally mounted on said head at one side of the free end of said. arm member, said finger beingformedwith aprojection at its intermediate portionY that is Vin contact withsaid roller; a tension spring attached to the free end of said tripping. finger and extendingforwardly therefrom withinsaid head; a flexible element secured to lthe frontend of' said spring; and a pulley mounted within said head, said cable passing around said pulley to said hook.

3. An adjustable torque wrench as -set forth in c1aint2 which includes a set screw mounted on said trippingfinger between its free end and said projection that normally engages said roller so as to control the wedging angle between said projection and saidroller.

4. An adjustable torque wrench as set forth in claim 2 where said roller is formed with a notch for receivingsaidprojection.

5. An adjustable torque wrench as set forth in claim 4 which includes la set screwbetween its free end andsaid, projection that normally engagessaid rollerV so astocontrol the wedging angle between said projection and the. sides of saidv notch. v

6. An adjustable torquewrench comprising; a. head; a load-engaging member pivotally mounted atfthe frontY portion of said head; a lever extending away from the rearI of said head; a rigid arm member rigidly secured to saidv load-engaging member and extending generally rearwardly therefrom; a tripping finger pivotally mounted o n said. head for rotation towardand away from thefreczendzof said arm member; resilientmeans attached to.the, frec. end of said finger for constantly biasingI the intermediate portion thereof into contact with the free end of saidfarm member; and means for adjusting the wedging angle bctween the intermediate portion of said tingerand theV free end of said arm member independently of said resilienty means.

Referencesv Cited, in theftile of this. patent UNITED STATES PATENTS 2,172,561 Kruse --.sept 12,1939; 2,556,587 Keen June 1'2, 1 9 5l 2,667,800 Garwood' Feb. 2, 1954 FOREIGN PATENTS 109,874 Australia Feb. 20, A194i)y 717,570' Germanyv uFebfl; 1942 565,315 Great Britain ..iNoin '6919444- .701.604. GreatBritain Dec. 30, 19,53 

